Satellite navigation systems are vulnerable, warns report

A new report warns that society has become ‘dangerously over-reliant’ on satellite navigation systems, just two weeks after such a system was declared safe for guiding aircraft from space.

The report, by the Royal Academy of Engineering, focuses on our increasing reliance on global navigation satellite systems (GNSS) and the current limited use of GNSS-independent back-ups. It also highlights the vulnerability of GNSS to interference — both artificial, through surreptitious ‘jamming’, and natural, from solar flares and space weather.

The report comes after the European Geostationary Navigation Overlay Service (EGNOS) was certified for ‘safety-of-life’ operation in aviation — for the first time, space-based navigation signals have become officially usable for the critical task of vertically guiding aircraft during landing approaches.

EGNOS works through a network of 40 ground stations that gather positional data from the US-run Global Positioning System (GPS) and beams that up to transponders aboard three satellites in geostationary orbits over Europe (part of the planned Galileo system). The more precise, amalgamated data is then sent back down to receivers aboard aircraft or other vehicles.

The EGNOS Open Service was launched in October 2009, for navigation applications where the safety of human life is not at stake, such as personal navigation, goods tracking and precision farming.

Now that it has been certified for aviation, it is hoped that EGNOS will be particularly valuable in poor weather or at airfields too small to invest in expensive, ground-based landing systems. The signal is a free-to-use public service and private companies are being encouraged to develop receivers capable of exploiting it.

Despite concerns outlined in the report, co-author Prof Washington Yotto Ochieng of Imperial College, London, said it is simply part of the process of checks and balances to improve systems such as EGNOS and eventually Galileo — which he insists have huge potential benefits.

‘If you asked me: “is it going to be is possible to do gate-to-gate navigation of aircraft solely from space?”, my answer would be yes, but we have to look at failure modes.

‘As part of the process of utilising this really important infrastructure, what we are asking is how might the system fail, and are the barriers we have in place today able to protect us, or do we need to do more research and development?’ Ochieng said.

The report makes several recommendations, calling for greater awareness generally; for government policy to better prevent surreptitious jamming; for more robust antenna and receiver hardware; and for potential back-up solutions, such as the land-based eLoran radio-navigation system.

‘GPS is being modernised as we speak, while Galileo is being developed with experience of us having observed GPS for many years, so Galileo will take into account some of the weaknesses of GPS. The Russian GLONASS system is being revamped, the Chinese have BeiDou and there are various countries, such as India, with EGNOS-like augmentations.